Investigation of microwave generation by intense relativistic E-beams

Microwave emission from a relativistic electron beam propagating in uniform and rippled magnetic fields has been investigated in a wide frequency range (12 GHz – 110 GHz). The electron beam generator is connected to a foil less diode immersed in a uniform magnetic field. The beam (V=750 KV and 1=5 10 KA) is propagated in a stainless steel drift tube parallel to an external magnetic field of up to 40 KGauss. Different foil less diode configurations and drift tube diameters were investigated. The properties of the beam have been measured using Faraday cups, damage plates, calorimeters and X-ray monitors. Results of microwave generation in uniform and rippled magnetic fields using different diodes and different beam parameters will be presented and discussed. Also, the influence of the strength and the period of the rippled magnetic field on the radiated power will be analysed. Computer simulations of the beam behavior were carried out for the different cathode-drift tube configurations. The computer results will be compared with the measured beam properties.